Beavers

Identification | Biology | Damage Id | Management | Resources

Figure 1. Beaver (Castor canadensis).
Image by USDI-Fish and Wildlife Service (USFWS).

Identification

Beavers (Castor canadensis, Figure 1) are the largest rodents in North America. They are mainly aquatic and easily recognized by their large, flat tail.

Legal Status

The legal status of beavers varies among states. In some states, beavers are protected except during furbearer seasons. At other times, they are classified as pests and may be taken whenever they cause damage. Beavers generally are not considered pests until economic loss is extensive. Consult your state regulations for additional information related to the management of beavers.

Physical Description

Beavers can remain submerged underwater for long periods of time. Beavers have a valvular nose and ears, and lips that close behind the 4 large incisor teeth. The underfur is dense and generally gray in color. The guard hair is long, coarse, and ranging in color from yellow-brown to black, with red-brown as the most common coloration. The prominent tail is flattened dorsoventrally, scaled, and nearly hairless. It is used as a rudder when swimming, a warning signal when slapped on the water, and a prop when sitting upright. Beavers have large, bright orange, front incisor teeth that grow continuously throughout their lives. The incisors are beveled, and sharpened through gnawing and chewing.

The only way to externally distinguish the sex of a beaver, unless it is a lactating female, is to feel for the presence of a baculum (a bone in the penis).Adult beavers typically weigh 35 to 50 pounds, with some reaching 70 to 85 pounds and a few over 100 pounds.

Species Range

Beavers are found throughout most of North America (Figure 2).


Figure 2. Distribution of the beaver in North America. Image by Prevention and Control of Wildlife Damage.

Voice and Sounds

Beavers use their tails to warn others of danger by abruptly slapping the surface of the water. Beavers have several vocalizations, including churrs, mumbles, whines, snorts, and hisses.

Tracks and Signs

The feet of beavers have 5 digits. The hind feet are webbed between digits. The front feet are small in comparison to the hind feet (Figure 3).

Tracks of beaver.

Signs of beavers include flooding and removal of plant material, such as trees or garden plants (Figure 4).


Figure 4. Tree cut down by a beaver.
Photo by Stephen M. Vantassel.

Biological Information about beavers